Managua's million or so residents have been uneasily sitting out the recent tremors that rock the furniture and make the drinking water splash in containers. They are waiting for the next big one. The last earthquake, in 1972, destroyed most of the city. From the park up on a hill, you'd be forgiven for thinking that afterwards Nicaragua's capital was reconstructed as a garden city, because the greenery hides all but a sprinkling of buildings that are two storeys or more.

Up here, the giant metal silhouette of Sandino towers over the ruins of the old Somoza palace and the bunkers where Sandinista revolutionaries were tortured. Nothing can be seen of the great sprawl of concrete block houses that were built after the old ones fell down.

The view from here at sunset is incredible. A jungle of trees stretches in every direction, and Lake Nicaragua, the hills and Momotombo volcano in the west fade out in a pinky-blue haze. The only blot on the landscape comes from the great pall of smoke at one side of the lake – a landfill site, La Chureca.

The hundreds of families who live at La Chureca don't have the luxury of concrete block houses. They live in shelters made of whatever they can find on the rubbish dump. They pick over the rubbish brought in daily, for food to eat and for anything that can be recycled and sold.

Some of the children go to school. But many more have to work for their families, sifting through the rubbish among the fires, or poking through the mud when the rains come. They have old people's faces, and grubby little bodies.

The lucky ones who come to the Los Quinchos Centre at La Chureca for their lunch of rice and beans after a morning's work have ready smiles as they wait patiently for their turn at table. Others are even more fortunate. They have spent the morning here, doing puzzles, colouring-in, copying sentences and numbers, making hammocks. One little boy describes his colouring-in to me. There's a house, with a roof, windows and a door. A bright yellow sun and two clouds in a deep blue sky. Trees in the garden.

It's a classic child's picture. Well, almost ... When I ask about the birds in the drawing, he tells me they are vultures – the only birds he knows.